Devices for sliding or gliding over water, snow or ice, such as skis, surfboards, water skis and the like and particularly cross-country or touring skis, typically have the running surface, which is frictionally engaged with the water, snow or ice, treated or designed to reduce friction or to provide better control or stability. Treatment of cross-country skis has been accomplished by applying wax to the running surface.
The running surface of skis also has been modified structurally, particularly cross-country skis, to provide scale-like protuberances on the bottom surface of the skis. Such protuberances have been employed on one surface of a polymeric thermoplastic ski base, which base is then secured to the bottom surface of a ski. The use of three-dimensional scale formations on the running surface of a ski, to provide control and stability with respect to climbing, tracking and other ski maneuvers, has been set forth in U.S. Pat. No. 3,408,086, hereby incorporated by reference. This patent discloses the employment of rows of protuberances with curved edges along the running surface in a regular repeating pattern over the gliding surface of the ski.
U.S. Pat. No. 3,858,894, hereby incorporated by reference, is directed to an improvement of the above patent in which protuberances, particularly trapezoidal-type formations, are nonharmonically spaced to eliminate or reduce the noise level during gliding movement of the ski.
In addition, different variations of protuberances have been known for some time. Such variations have not fully satisfied the requirements of skiers as to friction, stability or control and other desirable properties (see, for example, U.S. Pat. No. 3,381,972 and German Pat. Nos. 273,954; 870,369; 1,578,922; and 1,950,327).